Piston



March 3 1954 c. w. MORRISON ETAL PISTON Filed Dec. 27, 1950 Y E m v M mi a 7 N r r r W? W M I mm 0 wmb I00 00R Y B Patented Mar. 30, 1954 PISTON Clyde W. Morrison and James G. Bonine, Toledo, and Robert E. Marisay, Woodville, Ohio, assignors to The Metal Electric Processing Company, Toledo, Ohio, a corporation of Ohio Application December 2'7, 1950, Serial N 0. 202,858

1 Claim. 1

This invention relates to pistons such, for example, as are used in compressors for domestic refrigerators, and to the method of making same.

An object is to produce a newand improved piston assembly of the above character, which is made up of two parts, an apertured sheet metal tube to which harmonic motion may be imparted in the usual manner by a revoluble crank pin, and a piston, one end of which has an enlarged surface for contact with the side of the tube to which it is brazed.

Another object is to produce a method of forming a piston and tube assembly by which the two parts can be readily and conveniently formed individually, and efficiently and economically assembled, so that in eifect a unitary structure is produced which is light in weight, sturdy and rigid in construction, requires a minimum of machining, enables the use of flat heet metal for one part, and effects a liquid-tight seal between the parts.

A further object is to produce a piston and tube assembly of the above character which has enlarged contact area between the parts to insure a rigid joint liquid-tightin its nature, the same being light in weight, and inexpensive to manufacture on a quantity basis.

Other object and advantage will hereinafter appear, and for purposes of illustration but not of limitation, embodiments of the invention are shown on the accompanying drawings, in which Figure 1 is a perspective view of the tube and piston assembly;

Figure 2 is an elevational view partly in section of the assembly shown in Figure 1;

Figure 3 is a side elevation of the assembly shown in Figure 1;

Figure 4 is a perspective view of the apertured sheet metal strip before it is rolled to form the tube;

Figure 5 is a top perspective view of the piston with its end formed to conform to and fit the tube;

Figure 6 is a side elevation of an alternate form of a drawn shell; and

Figure '7 is an enlarged fragmentary sectional view showing a means for holding the part in assembled relation preliminary to the controlled atmosphere brazing.

The illustrated embodiment of the invention comprises a tube and piston assembly, the parts of which consist of a piston l0 and a tube ll rigidly joined to the piston. By way of example, this assembly is adapted for use in a refrigerator compressor, the piston reciprocating in the usual 2 manner within a cylinder and the tube I I having aligned lateral openings l2 of longitudinally elongate form to receive a slide on the end of a revoluble crank pin thus producing the wellknown harmonic or Scotch motion. The piston I0 is cylindrical and in one form, the outer end is closed by a disc I 3 which fits snugly inside the piston and is brazed in a controlled atmosphere to effect a rigid fluid-tight seal.

An alternate form of the piston is shown in Figure 6 which instead of being formed from a tube, is in the form of a drawn shell having an:

integral and wall [3a.

The inner end of the piston is formed in a suitable manner to provide laterally extendingend flanges I4 and upstanding side flanges l5 which conform to and lit the outer contour of the tube H in the region between the aligned aper tures l2. By forming the inner end of the pis ton in this manner, an enlarged surface contact between the end of the piston and the tube can be achieved so that when the parts are brazed together, this increased surface aifords the opportunity of efiecting a very secure, rigid and leakproof joint between these parts so that for all practical purposes, a one-piece unitary assembly i produced.

The tube H is formed from a strip A of sheet metal in which the holes [2 are first blanked whereupon the strip is rolled to form a tube with the free edges in abutting relation as indicated at B on Figure 2. The tube and piston are assembled with these abutting edges disposed within the formed end of the piston so that in the subsequent brazing operation, not only is the piston rigidly secured to the tube, but also the abutting edge portions of the tube are secured together to provide in effect a continuous walled tube.

It will be understood that after the parts are formed as above explained, they are introduced in a brazing furnace and it is therefore necessary temporarily to attach these parts together so that they will be properly retained in position during the brazing operation. For this purpose, the parts may be connected together by projection welding in a resistance welder, or tack welded, this being indicated on Figure 2 at C. Alternatively, the upstanding flanges [5 Which preferably reach close to the edges of the openings l2, may be crimped over as indicated at Hi, to provide the temporary connecting means. Thereafter, the assembly i introduced into the furnace and the formed end of the piston as well as the 3 abutting edges B of the tube II, and where a separate disc I3 is used, are all brazed in a controlled atmosphere to effect the desired rigid leak-proof joint.

The advantages of the above described assembly are numerous. In the first place, the assembly is very light in weight and this is important not only from thestandp'oint of performance but also from the standpoint of material cost saving.

This structure can be completed readily for use i with a minimum of machining, a small amount of finish machining being required. The rigid joint between the parts not only provides, the

equivalent of a one-piece structure, but also seals the inside of the piston against the entrance of oil or the like which would not only be deleterious but would also interfere with the proper operation of the piston. By making the piston of tubing or drawn shell, the proper outside diameterca'n be secured with but little. finish machining. Also by employing a rolled blank to produce the tube, machining costs on all surfaces are saved.

It i to be understood that numerous changes in details of construction, arrangement" and choice of materials may' be eifected without departing from the spirit of theinvention especially' as defined-in the appended claim.

;posite sides of the abutting edges, and a brazed joint between the flanged piston end portion and the tube and between the abutting tube edges thereby rigidly connecting the parts and sealing the interior of the, piston.

CLYDE W. MORRISON. JAMES G. BONINE. ROBERT E. MARISAY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,860,141 Ducommun May 24, 1932 1,862,251 Armentrout' Jun 7,1932 2,148,423 Ble'tt'ner' Feb. 28, 1939 2,244,954 hewza June 10, 1941 2,404,651 Olin July 23,1946 2,513,514 Poag'e July 4, 1950 

